1. With a fork mix together the ricotta, lemon zest, pecorino and most of the parmesan, and season carefully.
2. Fill the tortellini with a teaspoon of filling and cook in boiling salted water for 3 – 4 minutes.
3. Heat a large frying pan, add the butter and sage and cook until the sage is crisp and the butter is foaming but not colouring.
4. Throw in the drained tortellini and squeeze in some of the lemon juice to taste.
5. Serve immediately and sprinkle generously with the remaining parmesan

Tip: If you are using freshly made pasta, roll it out to the thinnest setting and then lay it on a floured bench. Place teaspoons of the mixture at intervals about 1 cm from the edge. Fold over the pasta to enclose and seal (can brush a little water along the edge before folding over to assist with sealing). Cut up using a fluted pasta wheel.